Wireless network infrastructure equipment is increasingly being used to allow computing devices to communicate over a wireless medium to a wired network such as the Internet. In a wireless data network, a plurality of local computing devices, such as PCs, are supported via wireless subscriber access units. A subscriber access unit provides a wireless radio link to a base station processor. The base station processor is also connected to an Internet gateway that provides a connection to a wired network. Similar to a cellular telephone network, the base station processor allocates a plurality of wireless channels on a demand basis for providing message transmission to and from the subscriber units. The wireless channels are allocated to messages sent and received from the subscriber unit on behalf of the local computing device.
In a typical base station processor, the wireless channels are a scarce resource which are shared by the subscriber units. Messages are often queued pending availability of a channel. Further, wired networks typically employ techniques to detect the speed with which a recipient is processing messages. These techniques reduce congestion by avoiding overburdening a recipient through reducing the rate at which messages are sent, and consequentially reducing throughput. Such techniques can interpret the queuing of messages at the base station processor as congestion in the wired network, and accordingly, reduce throughput. In particular, the protocols employed in the wired network do not lend themselves well to efficient communication over wireless connections.
In a TCP/IP network, for example, congestion control techniques such as slow start, congestion avoidance, fast retransmit, and fast recovery are employed. In accordance with the slow start technique, as defined in Internet RFC 2581, an acknowledgement message (ack) is expected as a return message to each message sent. The number of bytes, or messages, sent is gradually increased as the acks are received in a timely manner. If the ack is not received in a timely manner, additional messages will be sent less frequently, reducing throughput. The queuing of messages at the base station processor, however, is not indicative of congestion at the base station processor. Rather, the queuing is indicative of the propagation delay inherent in wireless networks. This propagation delay in interpreted, however, as congestion by the wired line protocols such as TCP/IP.
It would be beneficial therefore, to provide a method and apparatus which can anticipated the arrival of the return message, and schedule a channel to be available to transmit the message via the base station processor so that throughput in the wireless network is not reduced by the wired network protocol congestion control features such as slow start.